Perlite sound absorbing plate and sound insulating wall composed of the same

A sound insulating wall comprising a plurality of equally spaced apart and vertically extending end and intermediate supporting columns each having a lower portion embedded in foundation ground and provided at its at least one side surface with a groove, a number of perlite sound absorbing plates each provided at its side surfaces with a side groove and arranged side by side in both horizontal and vertical directions, a plurality of equally spaced apart and horizontally extending upper, intermediate and lower reinforcing plates each provided at its at least one surface with a ridge engaged with said side groove of said perlite sound absorbing plate and at its both ends with projections engaged with said groove of said supporting column, said perlite sound absorbing plate being arranged side by side directly between said supporting columns in horizontal direction and through said intermediate reinforcing plate between said upper and lower reinforcing plates in vertical direction, and being composed of a mixture including 1,000 cm.sup.3 by bulk volume of foamed perlite particles each having a diameter of 0.1 to 7.0 mm, 10 to 140 g of cement, liquid rubber latex containing 5 to 20 g of solid ingredients and a suitable amount of water and produced by agitating said mixture, charging said agitated mixture into a desired metal mold, press molding with a compression ratio of 1.10 to 1.30 to form a molded plate and curing and hardening said molded plate into a final plate.